Snack products of thin, relatively flat shape have unique advantages in processing and marketing as a consumer product. Potato chips, for example, are well-known snack products prepared by frying thin slices of raw fresh potatoes. Because of their thin dimension, water is rapidly removed from the potato slices during frying, forming a snack product with crisp texture and a fresh potato flavor. Extruded and sheeted fried snack products made in a thin, flat shape from ground precooked corn have the same advantages of fast frying to an acceptably low moisture content and a crisp texture.
Many processes have been developed for producing thin fried snack products from a dough which is prepared, formed and cut into desired shapes, and then fried. An especially large number of processes have produced such fried snacks from a potato-based dough, but none has had the commercial success of fresh potato chips. A number of these potato-based processes are described in my U.S. Pat. No. 3,886,291, from column 1, line 35 to column 3, line 23.
Generally, processes for frying dough pieces that have been sheeted and cut into desired shapes can be separated into two catergories. The most common of these processes involves deep fat frying the dough pieces without mechanically shaping them during drying, resulting in products that are randomly shaped. The shape can be controlled only to a limited degree in the fryer by the stiffness of the dough pieces and the velocity of the frying oil. Large stiff dough pieces that fry to a relatively flat shape without curving are often considered undesirable because they stack together in packages, increasing the bulk density and presenting a generally unattractive appearance.
The second category of fried snack products made from thin, flat dough pieces includes those in which the dough piece is mechanically shaped during frying. In U.S. Pat. No. 3,132,949 to Crowe, flat sheeted cut pieces of a corn-based dough are fried; and as the pieces rise in the fryer due to accumulation of steam on the underside of the pieces, they are constrained by the curved shaped of a wire cloth suspended under the surface of the oil. This causes the shape of the pieces to conform to the curvature of the wire cloth. In U.S. Pat. No. 3,149,978 to Anderson et al., round corn chips are subjected to a mechanical force during deep fat frying, while the chips are sufficiently plastic. This imparts a bent configuration to the finished chips. In U.S. Pat. No. 3,394,646 to Cunningham et al., round discs are formed from corn masa by the concave configuration of a cupped surface that forms the dough piece. In U.S. Pat. No. 3,653,335 to Griner et al., dough pieces are shaped into a scoop portion and finger-grip portion by a complex mechanical forming machine. U.S. Pat. No. 3,966,983 to Dexter et al. describes maintaining thinly cut dough strips in a straight configuration by spraying oil on the product while it rests on a supporting belt before entering the fryer.
A number of fabricated potato chip processes use perforated metal forming devices to hold dough pieces during frying to form uniformly shaped chip-type products. These processes are described, for example, in U.S. Pat. No. 3,520,248 to MacKendrick, and U.S. Pat. Nos. 3,576,647; 3,608,474; 3,626,466; and 3,998,975 to Liepa.
In another process for making fabricated potato chips, a dough sheet is cut into a continuous ribbon of dough pieces passed through a deep fat fryer and later broken into individual chips. This process is described in U.S. Pat. No. 3,937,848 to Campbell et al. and U.S. Pat. Nos. 4,032,664 and 4,096,791 to Weiss et al.
When making fried snacks from thin, flat dough pieces, there is a tendency for the dough piece surfaces to separate and puff during frying. In snack products made from a dough with a reasonably high moisture content, say in the 35% to 60% range, it is desirable to produce a thin, uniformly expanded product upon frying. Normally frying such a thin moist dough piece produces large surface bubbles in the fried product. Such puffing or bubbling occurs because steam accumulates between the outer surfaces of the dough pieces during frying, especially in sheeted dough pieces when multiple reduction rolls have been used. Puffing and bubbling detract from the appearance of the finished snack and can cause the snack to fill with excess fat. Such separation or distortion of dough pieces in the fryer has also been referred to in the art as "pillowing" or "blistering", but the terms puffing or bubbling are used interchangeably herein for convenience to describe any of these phenomena.
A number of processing techniques have been devoted to reducing puffing in thin sheeted fried snacks. U.S. Pat. No. 2,905,559 to Anderson et al. describes a conventional "dockering" technique in which a corn masa dough sheet is perforated with small rigid spikes spaced about 1/8 to 1/2 inch apart. The perforations allow moisture from the dough to escape during frying, which avoids puffing of the finished fried product. U.S. Pat. No. 3,278,311 to Brown et al. discloses a process for making corn chips in which corn particles are forced through a plasticizer having a screw grinder with a perforated end plate. The plasticized dough is sheeted and then dockered, cut into pieces and fried in oil. U.S. Pat. No. 2,916,378 to Kunce et al. relies on coarsely ground corn in ordinary corn chips so that the dough surface is disconnected and the steam from within the dough can readily escape during frying to avoid puffing. U.S. Pat. No. 3,883,671 to Shatilla describes a process for reducing puffing by moistening the surfaces of flat dough pieces with water after forming and before frying. Other methods reported to reduce puffing include forming dough pieces with a corrugated surface, and forming the dough pieces in very thin layers of about 0.4 mm (0.016 in.) thickness.
It would be desirable to produce fried snacks with good flavor and a controlled curved shape from thin, flat dough pieces fried in a commercial process that does not require mechanical shaping of the dough pieces during frying, while avoiding puffing and excess fat uptake during frying. There are many difficulties to be encountered in producing such a product.
Flat dough pieces allowed to fry without mechanical constraints generally remain flat but can become randomly bent and have an unattractive appearance. The flat products have an undesirable high bulk density.
Fried snack products, particularly fabricated potato chips, which are made from flat formed dough pieces with mechanical constraints require complex and expensive forming equipment and nonconventional fryers. Further, because of the need to reduce volume in such fryers in order to avoid formation of free fatty acids, the frying time is commonly very short. It can be under 30 seconds, for example. This, in turn, limits the maximum initial water content of the dough to about 35%. Such a dry dough is difficult to form and produces a bland, unnatural flavor when fried. It is thought that typical potato flavor is absent from such products because flavor precursors present in the dry potato ingredients are not sufficiently hydrated and do not have time to react during the short frying interval to produce a characteristic fried potato flavor.
Processes in which dough pieces are mechanically constrained during frying normally produce fried products having an entirely uniform shape, and as a result, they appear artificial.
Attempts to reduce puffing in thin, flat fried snack products by mechanical dockering with rigid metal pins supported on cylindrical rollers have generally not been successful because the relatively large openings formed in the dough create an untypical appearance in the finished snack product. The products appear artificial because the large dockering holes have an identical pattern or a uniform repeat pattern in all of the finished snacks.
Attempts to control puffing by spraying water on the dough pieces can cause the pieces to become slippery and stick together during frying. Water spraying also requires more energy for subsequently removing the added water; and it forms a product with a hard, less desirable texture after frying.
The present invention provides a process for making a fried snack product from dough pieces fried so that their shape is controlled during frying to produce finished fried pieces of similar shape. Rather than being entirely uniformly shaped, the fried pieces appear as if made at random, in a manner similar to the random appearance of potato chips. The shape of the fried products is produced without use of mechanical molding or constraining devices during frying. Moreover, the fried snacks are produced from a dough having a relatively high moisture content. As a result, a frying time of 30 seconds or longer, preferably 60 seconds, can be used to prepare products which, when fried to completion, have a full characteristic fried flavor.
The invention includes a method for producing a novel two-layer fried snack product having a convexly curved shape which, in one embodiment, has an outer layer resembling the skin of a baked potato and an inner layer resembling the interior portion of a baked potato. These novel products are made from thin, flat layered dough pieces fried in oil without mechanical forming or constraints for shaping the dough pieces. During frying, a natural-appearing curved shape is imparted to the layered dough pieces. One embodiment of the invention controls the dough pieces during frying so that layers resembling the darker skin of a baked potato are consistently on the convexly curved outer sides of the finished products, while the layers resembling the lighter interior portion of a baked potato are on the concavely curved insides of the finished products.
The invention also provides novel dockering techniques that produce single layer and double layer finished products without undesired puffing or bubbling, while avoiding water spraying and problems associated with dockering rolls having rigid metal pins. The dockering method also avoids other problems resulting from dockering techniques of the prior art. In addition, use of the dockering method produces novel fried products.